Supports transparency of the active image so it can be aligned with the image data underneath.

Selection of fiducial points can be done with the mouse (an origin and a target as a Line Selction) for easy alignment. First select the Line Selection. Click on a landmark in the active image (i.e. the image selected with the radio buttons). The landmark point is the first point of the line selection, then select the target point (second or end point of the line selection) and press the Fiducial button. The active image should be positioned according to the line selection.